Agharta Network Upgrade Adopts Constantinople/Petersburg

Ethereum Classic activated the Agharta network upgrade at block 9,573,000 on January 12, 2020, implementing Ethereum's Constantinople and Petersburg features. Agharta was specified in ECIP-1056.

## Included EIPs

- **EIP-145 — Bitwise Shifting Instructions**: Added native SHL (shift left), SHR (logical shift right), and SAR (arithmetic shift right) opcodes. Before Agharta, bit shifting required expensive arithmetic (MUL/DIV with powers of 2) at 5+ gas. Native shifts cost 3 gas and enable efficient binary data manipulation.
- **EIP-1014 — CREATE2**: Deploys contracts at deterministic addresses calculated as keccak256(0xff, deployer, salt, bytecode_hash). The address is known before deployment, enabling counterfactual instantiation — contracts can be referenced before they exist on-chain. Foundation for state channels, factory patterns, and governance contracts.
- **EIP-1052 — EXTCODEHASH**: Returns the keccak256 hash of an account's code in a single opcode (700 gas flat). Previously required EXTCODECOPY to copy entire bytecode then hash it — cost scaled with code size. Enables efficient proxy pattern verification and contract identity checks.

## Note on EIP-1283

EIP-1283 (net gas metering for SSTORE) was not included. Ethereum itself removed EIP-1283 in the Petersburg fork after a reentrancy vulnerability was discovered. The SSTORE rebalancing was later reintroduced safely as EIP-2200 in the Phoenix upgrade (ECIP-1088).

## Client Requirements

- Core-Geth v1.11.6 or later
- Hyperledger Besu with ETC Agharta support